Messages in this thread |  | | | Date | Fri, 16 Mar 2012 11:24:47 -0400 | | Subject | Building BarGraph with LED subsystem | | From | simon@mungewel ... |
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Hi all, I have a couple of questions about the (user-land) use of the LED subsystem.
I recently offered a patch for controlling the LEDs of the G27 gaming wheel, on which the LEDs are arranged in a bar-graph of 5 to show simulation RPM. The suggestion was to use the LED subsystem, which this patch implements.
http://www.spinics.net/lists/linux-input/msg19747.html
Thinking further about how to about how to control this I was wondering whether a 'threshold' trigger would be useful. This would allow the use of value (uint?) to be compare against a threshold and the LED turned on/off automatically.
The main benefit of doing this as a 'trigger' is that we could 'link' (or 'sync') multiple LEDs to use the same value input, thus making the user-land stuff trivial.
Concept - ledtrig-thres would provide the controls: threshold - value to compare against. value - incoming value, if >= threshold LED is lit, if < threshold LED is dark. link - 'none' (standalone comparison), or the path to the value of another LED's value to use (ie '/sys/leds/my_device::2/value')
Comments? Is this all too complex?
Also I have a question about the default permissions on the LED controls; Is it possible to register LEDs so that users have write permission? At present the controls are only accessible as root.
Many thanks, Simon.
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